California Gov. Jerry Brown (D), accompanied by California Attorney General Xavier Becerra (D), responds to remarks made last week during a visit to California by Attorney General Jeff Sessions. (Rich Pedroncelli/AP)

SAN DIEGO — On the eve of President Trump’s first visit to California since taking office, the state’s Democratic governor, Jerry Brown, is questioning Trump’s decision to highlight prototypes for his promised U.S.-Mexico border wall.

“You see, in California we are focusing on bridges, not walls,” Brown writes in a letter to Trump that Brown’s office released Monday morning.

In the letter, Brown encourages Trump to visit the state’s Central Valley, where preparations are underway for a bullet train from San Francisco to Los Angeles — including the construction of bridges to accommodate the high-speed line — and touts the diversity of a state that on its own is the sixth largest economy in the world.

“California thrives because we welcome immigrants and innovators from across the globe,” Brown says in the letter, in which he also says that “our prosperity is not built on isolation.”

Upon arriving in the nation’s most populous state on Tuesday, Trump plans to visit the site near here of eight border-wall prototypes that are being tested by the Department of Homeland Security. The prototypes are a key early step toward fulfilling Trump’s marquee campaign promise.

He is also scheduled to give an address here to military members at the Marine Corps Air Station Miramar and attend a Republican fundraiser in Beverly Hills.

In his letter, Brown notes that other presidents have used their inaugural visits to California to celebrate diversity.

Brown cites the visits of President Harry S. Truman, who in 1945 witnessed the signing of the U.N. charter in San Francisco, and of President Lyndon B. Johnson, who in 1964 met with the president of Mexico.

Last month, Mexican President Enrique Peña Nieto scrapped plans to make his first visit to the White House to meet with Trump after a testy phone call between the two leaders ended in an impasse over Trump’s promised border wall.

Brown also notes in his letter that during his first visit to California, President George W. Bush acknowledged the importance of California to the nation’s economy.

“For decades, California has been the place where the future happens first,” Bush said. “Your continuing success is essential to the continuing success of the U.S. economy.”

Brown accused the Trump administration last week of being “at war” with California after it filed a lawsuit against the state targeting its “sanctuary city” laws meant to protect undocumented immigrants.

Also in anticipation of Trump’s visit, California Attorney General Xavier Becerra (D) is scheduled to hold a conference call with reporters Monday to talk about what he thinks should be the focus of the president’s visit.

Becerra has filed 28 lawsuits against the Trump administration seeking to block an array of federal initiatives, including the border wall.